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Snails are active at Mount Barker and South Stirlings after recent rainfall

Small pointed (conical) snails are active and feeding near Mount Barker and South Stirlings in response to rainfall that was recently received in the area.

The snail activity at South Stirlings was detected by a remote camera that is being monitored by the Stirlings to Coast farmer group as part of the WA Snail Mitigation Project funded by the Agribusiness Food and Trade Directorate

DPIRD staff and the South East Premium Wheat Growers Association (SEPWA) farmer group are also working on this project. There are also other cameras monitoring snail and slug movements at; Mount Barker, Munglinup, Gibson and Condingup.

A nearby grower at South Stirlings has also found dead snails on test patches of snail baits.

A dissection of snails from Mount Barker by DPIRD staff earlier this week revealed that the albumen glands had not yet started to develop which meant that the snails were not laying eggs then, but egg laying can be expected to begin in the near future. Further albumen dissections will be carried out by DPIRD staff and the PestFax team will keep readers informed of future albumen gland dissection outcomes.

There are three snail species that are pests of WA broadacre crops. For more information on how to diagnose snails refer to Diagnosing snails in crops.

Snails are hermaphrodites which enable both members of a mating couple to lay eggs. Mating usually takes place from mid-autumn to mid-winter when favourable moist conditions prevail after their long summer aestivation. 2-4 weeks after mating, spherical pearl-white eggs are laid into moist soil. Egg laying can continue from the break of the season to late winter. After laying, eggs hatch in 2-4 weeks, the young snails usually become sexually mature after one year.

Snail numbers should be monitored to determine if they exceed DPIRD’s suggested threshold numbers and if there is a need to carry out management methods.

Snails are usually found on stumps, fencelines and under stubbles, depending on the species of snail. A good way to determine snail numbers on open ground is to use a 32x32cm square quadrant and count all of the live snails in it. This is an area of 10% of a square metre so multiplying by 10 will give an estimate of snails per square metre.

Management options

Pre-seeding management options include; burning, grazing and tillage. Growers that have burnt need to be aware of surviving snails that may still be present and could cause risk to emerging canola crops. Control of summer weeds (green bridge) results in fewer snails being present in crops and also increases the effectiveness of baits by removing food competition.

After sowing baiting is the only control method. Snails can only be controlled by baits if they are mobile and looking for food. Young snails are not likely to be controlled by baits as they feed on decaying plant matter and are not likely to be attracted to baits. Baiting before the crop emerges is more effective because the pellets are not competing against the appealing green crop plants.

Entomologist Svetlana Micic (DPIRD) recommends that if you do have snails consider baiting small patches and observe if snails are actively feeding. It is a good idea to bait the population before egg laying occurs.

It is also recommended that growers budget for more than one bait application.